<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>粘性定位</title>
    <style>
      body {
        height: 3000px;
      }
      .nav {
        position: sticky;
        top: 50px;
        width: 800px;
        height: 100px;
        background-color: blue;
        margin: 200px auto;
      }
    </style>
  </head>
  <body>
    <div class="nav">导航栏</div>
  </body>
</html>
